From: David Masover <ninja@...>
Date: 2009-02-12T09:20:27+09:00
Subject: Re: Ruby vs Perl performance

Michal Suchanek wrote:
> On 09/02/2009, David Masover <ninja@slaphack.com> wrote:
>
>   
>>  Either way, I would put the burden back on you. Why is this so dangerous?
>> Why is it any more dangerous than the other duck typing tricks Rubyists use
>> every day? Why shouldn't I be able to do:
>>
>>  a.method(:foo).unbind.bind(b)
>>
>>  when a and b aren't related, but I happen to know they share a common
>> theme? After all, what ties the method to the object -- isn't it mostly
>> going to be calling instance methods, and occasionally accessing instance
>> variables -- so why should 'self' be exempted from the "quacks like" rule?
>>
>>     
>
> Actually you sort of can except the binding is not permanent.
>   

No, I don't think so. I've tried in a method somewhat similar to yours, 
and I get the same results.

> module Kernel
>   

That's probably why. Everything includes Kernel, so if you grab an 
UnboundMethod from Kernel, you should be able to apply it everywhere.

Try this:

module Foo
  def foo
    :foo   #ok, I'm unimaginative
  end
end

Foo.instance_method(:foo).bind(Object.new).call

See what happens? Doesn't matter whether Foo is a class or a module, you 
can only bind methods of it to objects which are somehow its 
descendants. If it's a module, you can only do this to things which have 
included that module, making it somewhat less useful.

Speaking of which, modifying Kernel -- yet another thing more dangerous 
than letting UnboundMethods bind to anything.